Web components, like most objects, usually work with other objects to accomplish their tasks. There are several ways they can do this. They can use private helper objects (for example, JavaBeans components), they can share objects that are attributes of a public scope, they can use a database, and they can invoke other Web resources. The Java Servlet technology mechanisms that allow a Web component to invoke other Web resources are described in the section Invoking Other Web Resources (page 234).
Using Scope Objects
Collaborating Web components share information via objects maintained as attributes of four scope objects. These attributes are accessed with the [get|set]Attribute methods of the class representing the scope. ...